WiGig® has been attracting attention as a next-generation wireless LAN standard. With use of millimeter waves of 60 GHz band, WiGig realizes ultrafast wireless transmission at up to 6.75 GB/sec. Accordingly, antennas for 60 GHz band are likely to be mounted on commercial devices, such as PCs and smart phones, with a large market size, and are expected to have an increasing demand.
A known example of an antenna whose operation band is a millimeter wave band is a slotted waveguide tube array antenna made of a metallic waveguide tube having a plurality of slots in one surface of the waveguide tube. For such a slotted waveguide tube array antenna, it is important to reduce reflection occurring at each slot, because reflection occurring at each slot deteriorates reflection characteristics and causes gain reduction.
A known example of a slotted waveguide tube array antenna in which reflection occurring at each slot is reduced is a slotted waveguide tube array antenna disclosed in Patent Literature 1. The slotted waveguide tube array antenna disclosed in Patent Literature 1 is arranged such that a wall plate is provided inside the metallic waveguide tube having slots so that a wave reflected at each slot is canceled out by a wave reflected at the wall plate.